How Much Should Roofing Felt Overlap

The overlapping felt creates a secondary barrier for moisture and wicks water away from the shingles above and the sheathing below.

How much should roofing felt overlap. The drip edge should extend at least 2 inches on the roof. Position this strip so that it overhangs the top of the first sheet by 75mm. Make sure you have enough roof felt you don t want to have to stop mid way through the project to buy more felt. Must be installed at the rakes and eaves of the roof.

Using a downwards brushing motion firmly press the top layer of roofing felt onto the adhesive taking care to ensure that the strip of felt does not ripple or crease. The overlap of 3 8 should be followed consistently for a smooth look once the shingles are installed. These applications are ideal for flat roofs or protective surfaces under roof level decks. Do the other side of the roof the same way also with an overlap at the peak.

Work up the roof to the peak and fold felt over the top overlapping at least 3 inches and fasten it on both sides. If lap sealant is used simply apply a bead of sealant on top of the underlap ridge going all the way down the length of the ridge before the overlap ridge of the next panel is placed on top. Since you will have overlap between rows this works out to a total coverage area of 400 square feet the dimensions of a 20 x 20 roof. Nail along the top of this strip at 500mm.

Adjacent pieces of drip edge should overlap at least 2 inches 51 mm. In other words if the height of the roof drops by 2 inches for every 12 inches in length you will need to use sealant to strengthen the overlap barrier. Roofing felt is required to overlap 2 inches over the lower felt course. Tack the roofing felt down with 1 4 staples using an air compressor with a pneumatic stapler a hammer tacker or a staple gun every 12 inches.

If this felt is either incorrectly situated i e. One roll of conventional 15 felt covers 432 square feet 40 1 m 2. Where the sheets overlap apply roofing sheet adhesive using a disposable brush. Therefore a 2 inch overlap provides redundancy at the edges where the barrier is weakest.

The felt must be flush at the rake side edges have 4 inch overlaps where two pieces are joined and 6 inch overlaps on hips and ridges. The bottom course of felt on a roof called sarking felt ensures that all of the rainwater is correctly channeled into the gutter by protecting the eaves from any wind driven rain. However you must allow for overlaps on joints. Take your second length of felt.

Purchase an extra pack of felt in case you need more or end up damaging your first roll. Ensure that the felt lies flat and smooth before securing it. Some roofing felts are actually glued down. The vertical leg of the drip edge should be at least 1 5 inches wide and extend at least 0 25 inches below the sheathing.